top of the lawn

urban footpath | pavement | sidewalk astronomy from Central Park, New York City

Wednesday, December 14, 2005

20051213 - Magnificent Desolation

Buzz Aldrin described the lunar landscape when he walked across its surface in 1969 as "a magnificent desolation." Those words became crystallized for me during last night's observing session at the Top of the Lawn (TotL). I was captured and mesmerized by the detail and beauty of crater Bailly, prominently dimpling the bottom of Moon on the edge of the terminator. It was here that I transported to that world of grays and black, freezing in the darkness of shadow, boiling in the sun's light.

I had gone out for two observing sessions - one with the 6" F/6 reflector behind the statue inside the south end of Central Park. This was a 90 minute session began around 3:00pm for observing and sketching the eastern librated maria. I found that sketching with this setup is more comfortable since I can adjust the eyepiece to where I'm standing straight up and not crouching.

Later, I would meet up with Charlie and Kin at TotL. They each brought their binoculars and I brought the 4" Takahashi refractor. I arrived shortly after Charlie and when we were standing around talking during cool down, Charlie spotted a bright meteor falling to our west. He pointed and I looked around an even saw for it for a couple of seconds - very bright with "sparkles" in the ball and a short tail. That would be the brightest of a dozen meteors we would see collectively through out the night. Kin spotted 2, Charlie 4, and I saw 7. I saw two meteors falling together almost side by side just south east (from our perspective) of two landmark buildings on our southwestern horizon, The Beresford. At times I felt I saw other less bright meteors with peripheral vision though I didn't count nor mention them to the others. Perhaps, the same was happening for them. With a bright waxing gibbous Moon, no doubt there were others that just got washed out. In fact when we looked at M42, the nebula was suffered from a bright background sky.

I regret that I didn't pull out the notebook and begin to sketch what we were observing along the terminator in the south southwest of Moon. But kneeling on towels and slightly crouched to a refractor pointing almost zenith in teen degrees Fahrenheit is not conducive to sketching. (It is also apparently obvious how a tracking mount would be more convenient.) Really I chickened out. Visiting the sketch gallery in Belt of Venus, and following the links that Jeremy provides there, I let a lasting impression defeat me for the moment. Not next time.

Three nearly equal sized craters - Zucchius, Bettinus, and Kircher - arced above Bailly. One can see them lower left (8:00 to) to the great ray crater Tycho on Vern's blog. Charlie & I observed Bailly at 182x and even as high as 325x. (At 325x, the dirt on my lens really stood out.) In both cases the seeing held up, with only occasional blurring. The detail was amazing seeing small rilles and craterlets on the floor and north eastern rim. The crater was half in shadow, black, and half illuminated. A ridge appeared to run across the length of the crater with one prominent crater Bailly B with an encroaching smaller crater in its eastern wall, further west-northwest along this central ridge and where the shadow fell, part of another crater was observed. Three broad shadows ribbed along the southern rim of crater Bailly like pinstripes. Bailly B's was responsible for the one to the east, forming an hour glass shape. To the west the partial crater was responsible for the middle shadow on the wall, and we didn't identify what projected the third shadow, perhaps a peak on that ridge. This map image displays something similar to what we observed.

Nearby Bailly, we observed three interesting craters - Wargentin, Nasmyth, and Phocylides. It was evident that Nasmyth was on Moon first, later to be partially overlapped by Phocylides. Wargentin was Escher-esque as it appeared as a "raised plateau" contrasting with the depressed craters Nasmyth & Phocylides. (One can see this effect in the image referred to above for Bailly.) The shadow along its northeastern rim appeared proper and then a bright round crater floor. The southern wall's shadow was very pronounced but the interior part of this wall was not seen. Thus it appeared as if the plateau fell sharply along the south.

At the end of the session we would observe Saturn and Mars. I was surprised by what we saw of dinky, little Mars. The was an obvious upside "Y" shape running vertical to the disk in the eyepiece. I mentioned to Charlie that could be Syrtis Major. Checking Brian Tung's Mars Map it didn't show up. Returning to the app today, I setup the time for 14 Dec 2005 00:45 and there was Syrtis Major.

This past month or so has been mostly Solar System whether by day or by night. Sometimes I get into the challenge of the deep sky hunt for the urban astronomer that I almost ignore our closest neighbors in the shallow sky. Nice to know Moon can keep me at bay.

Monday, December 12, 2005

20051211 - Gallivanting along the Libration Zone

Session Name: 20051211.1855

Last night I focused on Moon's eastern libration zone. Clouds would blanket the sky but after I got some time in observing. I spent a considerable amount of time with Mare Marginis, Mare Smythii, and Mare Australe. I did look at Mare Humboldtianum, really to see how its location near the limb changed, watching it climb back to the farside.

I didn't venture far from home. I set up the homemade 6" F/6 reflector, known as Harry just across the street from my front door. There is a small courtyard there from where I could follow Moon before it is obstructed by my building to manhattan-south. Pages from my notebook appear below. (Note Mars in the lower left corner.)

I don't recall seeing as much detail of these features as I may have in the past. I attribute it to sketching where one pays a considerable amount of attention to detail - at least I try :^D Even the weather played a part, where the night before I had the 10" out up at TotL but felt this evening's session provided better seeing. The detail around Mare Australe was incredible, and unfortunately my sketching skills do not impart the fantastic detail and changing shades of the lunar surface. The serpentine-like crawl of the mare in front of (interior to) the large crater Lyot reminds me of the same undulating flow of Mare Frigoris. Like a personal asterism, Mare Frigoris' shape is felt all about the lunar disk in other features. A similar twisting shape is a feature just interior to Mare Marginis; Mare Anguis writhes east northeast of Mare Crisium.

In Mare Smythii, I could see two areas where craters were apparent. One to the north was fairly sizable, such that easy to pick up, and it was situated just beyond the darkening tip of the mare. The other was more central to the mare and could have been more than one craterlet. Like all features along the limb, its easy to imagine that these are round shapes, but when sketching long thin ellipses and polygons are more the case. When regarding the shapes and composing where they lie with relation to other features, the curvature of the lunar surface is really emphasized in the seeing. It was difficult to say whether the mare was entirely inside the limb. I noticed a peak and some "un-smoothness" along the limb and wondered if that was part of the mare's far eastern rim. Most of the time I felt the whole mare was on the lunar disk, albeit severely foreshortened. Finally, Mare Smythii contrasts significantly from maria Marginis & Australe in that it at least appears to be a large foreshortened round formation. The other two maria are splattered patches of dark colored floor, sometimes discontiguous or of animated shapes.

At first glance, Mare Marginis appears as a partial gingerbread man figure. Large crater Neper with two peaks, cheating to the south, sits between Smythii and Marginis. My notes state that it is nearly central but the sketch shows much closer to Marginis. I could check the atlas but hopefully tonight will be clear to validate it. On the northern end of mare between it and the limb, either a mare-floor feature or a crater was observed just interior to the limb.

----- ------- ------One can see how libration is favoring Mare Australe by visiting Vern's Blog. He has imaged three days of Moon: 12/07/2005, 12/08/2005, 12/11/2005. I downloaded the images and sequenced the 3 images. One can see how Mare Australe increasingly rolls on to the lunar disk. Conversely, one can see up along the northern limb, Mare Humboldtianum roll off the disk towards the farside. Changes with maria Marginis and Smythii are not as apparent.

I showed a few people Mars and observed for short period. The best magnification was 100x, 180x was pushing it. In addition to a few of the passersby, I could see a dark mare feature running slightly vertical across the disk in the field of view. Nothing more than that, other than it is growing smaller by the day.

Sunday, December 04, 2005

20051203 - The Sun and Crescents

Session Name: 20051203.0953

Set up at the Rock, a location at the south end of Central Park nearby Wollman Rink. The ice skating rink is partially visible through the trees.

It was a laborious session to say the least. The clouds kept coming in large, dark tufts from behind the buildings looking manhattan-south. The taller buildings rise about 23° in altitude so at times it looked as if the quick, moving clouds would yield large clear, blue sky but that wouldn't be the case. Seeing was poor and it was diffcult to use magnifications as much as 97x. I observed mostly at 63x and still had to wait for turbulence to settle. When showing Sol to the passersby, around 10 persons, I lowered it to 41x for a sharper image.

Earlier in the morning around 8:30, I held up the Baader film to Sun to see a large dark line in the center of the disk. Sun was rising into the CitiCorp building so when the building occulted the solar disk, I could see that the line was to the preceding side. Later during the observing session I had a difficut time seeing group 826 through the vieiwing window.

I continue to practice sketching. This session's sketch is below. For me, group 826 was very difficult to draw. The detail was amazing during steady moments, particularly the penumbra surrounding the following two spots of that group. Actually, the sketch shows those two spots and penumbra "larger than life". The area covered was smaller, and I estimate the length of the group relative to the separation of spot "A" to "C" to be between 1/3 and 1/2.

I finished up the session, observing Venus. I observed Venus in handheld 7x50 binoculars to confirm that the crescent shape can be discerned. I feel it is pretty easy to see when the bins are held firmly. Around the globe, Ian had recently wrote about this from Australia. While one is there, check out his image that displays Venutian changes in size and phase.

I was unable to observe Moon from where I was. The highest point it would reach would be 20°, and from the photo above one can see that there are windows of opportunity where the buildings are low. Today, the clouds were bad, obstructing the sky along this horizon. It wasn't until I arrived home and looked out our living room window, due manhattan-South, that I was able to see Moon. There was a 6.0% illuminated crescent about to set into the Rhiga Royal hotel.

At this time, both Venus and Moon are interior to our orbit around Sun and seen in the sky to the east of Sun. As a result, their crescents are illuminated on the same side. There is a difference, however, which of their phases they each approach. Moon, having passed New Moon phase, is waxing to First Quarter. Venus is waning to "New Venus" phase, where it will lie between Earth & Sun, after having passed greatest eastern elongation that had exhibited a last quarter. Check here for a more complete description of Venus phases; and, here for a desc ription of lunar phases.

Thursday, December 01, 2005

The Amateur Astronomer & Knowledge Level

An interesting study found on the Astronomy Education Review website. The study measures the knowledge level of amateur astronomers as affiliated and non-affiliated club members and discusses factors that contribute to their understanding. The study attempts to answer the following questions:

3. If they are knowledgeable, how much more knowledgeable are amateur astronomers about astronomy basics than are members of the public they serve?

Among the numerous observations and statistical measurements, outreach is a signicant part of the study to determine its contribution towards a greater understanding of basic astronomy concepts. The study's observations are informative, especially the relationships among club affiliation, outreach frequency, and level of knowledge, based on mean scores.

The actual "Astronomy Diagnostic Test Version 2" can be found here. It is same test used to measure incoming introductory astronomy students knowledge base and determine effectiveness of the coursework.